1. Field of the Invention
The present invention relates to an oil or fat (hereafter referred to as “oil” merely) composition which effectively develops physiological functions derived from ω3 type unsaturated fatty acids having at least 20 carbon atoms, such as inhibition of platelet aggregation, and is excellent in effect of facilitating combustion of body fat, oxidation stability, flowability, flavor and the like, and oral medicinal compositions and foods comprising such an oil composition.
2. Discussion of the Background
In recent years, it has been clarified that diglycerides can have an obesity-preventing effect, an effect to prevent an increase in weight, etc. (Japanese Patent Application Laid-Open No. 300828/1992, etc.), and it is attempted to incorporate these into various kinds of foods. It has been reported that when a glyceride mixture containing diglycerides at a high concentration is used in an oil phase, an edible oil-in-water type emulsion composition have a rich fatty feel and is good in flavor even when a fat content is decreased (Japanese Patent No. 2848849).
On the other hand, it has been known that ω3 type unsaturated fatty acids having at least 20 carbon atoms, such as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are mainly contained in the form of triglyceride in fish oil and the like in abundance and can have effective physiological activities such as anti-platelet aggregation property, antitumor activity, immune activation, antiallergic activity, improvement in brain function and improvement in visual function.
As oils highly containing such diglycerides and ω3 type unsaturated fatty acids, there have been known, for example, a natural oil that DHA among constitutive fatty acids of the oil is contained in a proportion of at least 60%, and the total content of diglycerides and monoglycerides is at least 80% of the oil (Japanese Patent Application Laid-Open No. 60181/1996), and the like.
However, the ω3 type unsaturated fatty acids having at least 20 carbon atoms are very poor in oxidation stability. When an ω3 type unsaturated fatty acid is oxidized, the oxidized unsaturated fatty acid involves a problem that not only its physiological activity functions are lost, but also the living body is adversely affected when such an unsaturated fatty acid is taken. In addition, an oil highly containing such an ω3 type unsaturated fatty acid has an unpleasant flavor derived from its raw oil, and so a problem is offered when it is used in food in particular. Further, ω3 type unsaturated fatty acids involve a problem that when they are converted into their corresponding diglycerides, the viscosity of the resulting diglycerides becomes high, so that the physiological activities of the ω3 type unsaturated fatty acids are hard to be developed.
It is therefore an object of the present invention to provide an oil composition which is good in flowability, resistance to oxidation and excellent in flavor, effectively develops physiological activities of an ω3 type unsaturated fatty acids having at least 20 carbon atoms, and is excellent in effect of facilitating combustion of body fat, and oral medicinal compositions and foods comprising such an oil composition.